A constant-load cycling exercise test will be performed to measure exercise tolerance at week 0, week 12 and week 52. Subjects will be seated on the same ergometer and connected to the same cardiorespiratory circuit. After 3min of unloaded pedalling, the workload will be set at 80% of the peak work rate achieved on the incremental cycling test. Patients will be asked to pedal against that workload for as long as possible. Inspiratory capacities will be obtained every other minute during the test to evaluate the degree of dynamic lung hyperinflation. Dyspnea and leg fatigue will be evaluated at rest and every other minute during the test with the modified 10-point Borg scale. The final measure for this test will be endurance time, defined as the duration of pedaling at a minimum of 40rpm at 80% of peak work rate.